Spring pin contactor



J 9 9- s. F. LYBARGER ET AL 2,143,564

SPRING PIN CONTACTOR Filed June 14, 1938 INVENTORS' Patented Jan. 10, 1939 UNlTE STAJES SPRING PIN CONTACTOR Samuel F. Lybarger and Alfred E. Pelz, Mount Lebanon, Pa, assignors to E. A. Myers & Sons,

Mount Lebanon, Pa,

a partnership composed of Edward A. Myers, Edwin J. Myers, Alfred E. Pelz, and Samuel F. Lybarger Application June 14,

9 Claims.

This invention relates to spring pin contactors such, for example, as form the electric plugs for connecting one hearing-aid instrument to another provided with a socket.

Spring pin contactors of this general type are generally formed with two substantially parallel prongs spaced apart to permit them to be flexed inwardly toward each other when they are inserted in a socket so that they will resiliently grip the socket and form a good mechanical and electrical connection. A difiiculty with such contractors has been that through wear, bending of the prongs or other causes they do not fit as snugly in a socket as they should, whereby a poor electrical connection may be obtained without the reason for it being realized.

It is among the objects of this invention to provide a spring pin contractor of simple and inexpensive construction with which a good mechanical and electrical connection with a socket member is assured at all times and which assures such connections even though the prongs of the pin are bent inwardly toward each other.

In accordance with this inventicn a metal contactor pin is provided with a stem adapted to be permanently connected to an electrical instrument, and a pair of spaced prongs for plugging into a socket in another instrument or the like. Disposed in the slot between the prongs is a wire spring loop at least one side portion of which projects from between the prongs so that it will be flexed inwardly when the prongs are inserted in the socket member. The resistance of the loop to being flexed inwardly causes it to resiliently grip the socket member and thereby hold the pin contactor in place even though the prongs fit rather loosely in the socket, and at the same time to provide a good electrical connection between the pin and socket. The normally projecting side portion of the loop is flattened or otherwise made thinner than the remaining portion thereof so that in case the prongs are accidentally pinched in tightly against the thicker portion of the spring loop the latter will prevent them from engaging the thinner portion which is thus left free to move in and out of the slot between the prongs so that the spring will continue to function. Furthermore, movement of the flattened portion of the spring is less likely to be affected by the possible accumulation of dirt between the spring and prongs.

The invention is illustrated in the accompanying drawing in which Fig. 1 is a side view of our spring pin contactor greatly enlarged; Fig. 2 is a vertical section showing the spring in eleva- 1938, Serial No. 213,612

tion; Fig. 3 is a plan or end view of the contactor; Fig. 4 is a view similar to Fig. 3 but with the pin prongs jammed inwardly against the thicker portion of the spring loop; Fig. 5 is a view similar to Fig. 2, but on a smaller scale, of a modified embodiment of this invention; and Fig. 6 is a view, similar to Fig. 1, of still another embodiment.

Referring to the first three figures of the drawmg, a metal pin, which in one embodiment is actually only about inch long, is provided with a threaded stem l by which the pin may be connected to an electrical instrument, such as a hearing-aid instrument, forming part of an electric circuit. The opposite end portion of the pin is of larger diameter than the stem and is bifurcated to form a pair of substantially parallel prongs 2 spaced apart to form a slot 3. In cross-section the prongs form segments of the same circle (Fig. 3) so that they will fit in a circular opening. The outer ends of the prongs are rounded off to facilitate their insertion in a socket member, not shown, their movement into the socket being limited by a collar 4 between the inner ends of the prongs and stem. These prongs are of such size that they can be resiliently distorted inwardly by the wall of the socket so as to frictionally grip that wall and also provide a good electrical connection therewith. However, it has been found that such a good connection is not assured, because wear of the socket and prongs, or permanent bending of the prongs, may cause a loose fit.

Accordingly, an independent spring member is placed between the prongs so that it also can resiliently engage the socket wall and not only improve the contact with it, but make a good contact in case the prongs do not. This spring member is in the form of a loop of spring wire disposed in slot 3 between the prongs with one end 6 extending away from the loop and anchored in the pin, preferably by securing it in an axial opening 'l in stem I, as shown in Fig. 2. Soldering has proven to be a very successful way of securing the wire in the stem as it provides a firm mechanical grip and a positive and noiseless electrical connection. This can be done by running the solder into the stem opening around the wire, as also shown in Fig. 2.

At least one, and preferably both, side portions of the spring loop normally project out from between the prongs so as to engage the wall of the socket member and be flexed inwardly thereby when the prongs are inserted in the socket. The side portion 8 of the loop immediately adjoining anchored end 6 does not have to normally project from slot 3, but a better contact may be secured if it does because the spring is rather stiif so close to the anchored end. The free end of the wire is turned back into the slot so that it will not catch on clothing or other things. When side portion 9 is flexed inwardly to the position shown in dotted lines in Fig. 2, the opposite side portion 8 is likewise sprung inwardly by engagement with the side wall of the socket, as also shown in dotted lines. The tendency of the loop to open up biases its side portions tightly against the socket wall and thereby greatly increases the effectiveness of the mechanical and electrical connection of the pin contactor with thesocket. This is especially true in cases where the prongs fit loosely in the socket, because the over-all width of the spring loop is considerably greater than the diameter of the contactor taken through the prongs. The reverse bend at the top of the loop (Fig. 2) is completely within slot 3 to prevent setting of the spring material and consequent loss of resiliency.

Another feature of this invention is that in case the prongs are jammed or otherwise pinched tightly against the spring loop it can still continue to function. This is made possible by flattening the laterally projecting side portion 9 of the loop (Fig. 3) relative to the remaining cylindrical portion 8 thereof which limits the distance that the prongs can be bent toward each other. Consequently, even though the prongs are jammed tightly against the loops thicker portion 8 so that it can not move, as shown in Fig. 4, the flattened portion remains spaced from the prongs and therefore is free to move inwardly and outwardly between the prongs to resiliently engage the wall of the socket. Because of this, the spring continues to function as a good contact element even though the prongs are bent. Another important function of flattening a portion of the spring loop, especially of the top part which has the greatest curvature, is to produce a marked increase in the spring resistance, because of the hardening efleot of such flattening of the spring material.

In the modified embodiment of the invention shown in Fig. 5, the free end ii of the loop is curved inwardly and then in a direction away from the stem so that its outer surface engages the inner surface of the side portion I2 of the loop immediately adjoining its stem end 83. The loop is preferably elliptical with both of its side portions normally projecting from between the prongs. Due to this construction the entire loop must be compressed in order to insert the pin in a socket, and the resistance to such compression is materially increased by having the free end of the spring engage one side of the loop. Another advantage is that the spring Wire is increased in length so that the distortion thereof is distributed over a greater area.

In this embodiment, as in the previous one, it is preferred to flatten the portion of the spring loop projecting from one side of the slot between the prongs. This can most conveniently be done if all of that portion is of the. loop from its outer end to the free end of the spring wire is flattened. Then, if the prongs are jammed against the thicker portion i2 of the loop, the remaining flattened portion M is free to flex and thereby continue good contact between the contactor and the socket that receives it.

Fig. 6 illustrates a pin contactor, provided with a spring loop i like either of the forms just described, in which slot it does not extend to the outer ends of the prongs i'i, whereby the outer ends of the prongs are integrally connected by a solid metal tie it. This type of contactor depends almost entirely upon the spring loop for holding it in a socket, because the prongs can not exert much pressure against the socket wall.

According to the provisions of the patent statutes, We have explained the principle and construction of our invention and have illustrated and described What we now consider to represent its best embodiment. However, we desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

We claim:

I. A spring pin contactor comprising a pin having a stem provided with an axial opening and a bifurcated portion forming a pair of spring prongs, and a looped wire spring disposed between the prongs with one end rigidly anchored in said stem opening, a side portion of said spring loop projecting laterally from between the prongs and being adapted to be sprung inwardly by engagement with a socket member to resiliently hold the pin in place.

2. A spring pin contactor comprising a pin provided with a slot extending longitudinally through its axis, and a looped wire spring disposed in said slot with one end of the loop anchored in the pin and the opposite end portion curved inwardly and extending away from its anchored end and adapted to bear against the side portion of the loop immediately adjoining its anchored end, the loop projecting laterally from said slot and being adapted to be flexed inwardly by engagement with a socket member to resiliently hold the pin in place.

3. A spring pin contactor comprising a pin having a stem provided with an axial opening and a bifurcated portion forming a pair of spring prongs, and a looped wire spring disposed between the prongs with one end rigidly secured in said stem opening and the opposite end portion curved inwardly and away from said stem with its outer surface in engagement with the inner surface of the side portion of the loop immediately adjoining its stem end, the loop projecting laterally from between the prongs and being adapted to be flexed inwardly by engagement with a socket member to resiliently hold the pin in place.

4. A spring pin contactor comprising a pin bifurcated to form a pair of spring prongs, and a looped wire spring disposed between the prongs, a side portion of said spring loop projecting from between the prongs and being adapted to be flexed inwardly by engagement with a socket member to resiliently hold the pin in place, said side portion of the spring being thinner than another portion thereof, whereby if the prongs are pinched inwardly against said other portion of the spring said thinner portion is still free to move between the prongs.

5. A spring pin contactor comprising a pin bifurcated to form a pair of spring prongs, and a looped wire spring disposed between the prongs, a side portion of said spring loop projecting from between the prongs and being adapted to be flexed inwardly by engagement with a socket member, said side portion of the spring being thinner than the opposite side portion, whereby if the prongs are compressed tightly against said opposite side portion of the spring said thinner portion is still free to move between the prongs.

6. A spring pin contactor comprising a pin bifurcated to form a pair of prongs, and a looped wire spring disposed between the prongs with one end of the loop anchored in the pin and the opposite end portion curved inwardly and adapted to bear against the side portion of the loop immediately adjoining its anchored end, the loop projecting laterally from between the prongs and being adapted to be flexed inwardly by engagement with a socket member to resiliently hold the pin in place, one projecting side portion of the loop being thinner than another portion thereof, whereby if the prongs are pinched inwardly against said other portion of the spring said thinner portion is still free to move between the prongs.

7. A spring pin contactor comprising a pin having a stem provided with an axial opening and a bifurcated portion forming a pair of prongs, and a looped wire spring disposed between the prongs with one end anchored in said stem opening and the opposite end portion curved inwardly and away from said stem with its outer surface in engagement with the inner surface of the side portion of the loop immediately adjoining its stem end, the loop projecting laterally from between the prongs and being adapted to be flexed inwardly by engagement with a socket member to resiliently hold the pin in place,

the side portion of the loop immediately adjoining said curved end being thinner than the opposite side portion, whereby if the prongs are compressed tightly against said opposite side portion of the spring said thinner portion is still free to move between the prongs.

8. A spring pin contactor comprising a pin provided with a slot extending longitudinally through its axis for only a portion of its length whereby the slot is closed at both ends, and a looped wire spring disposed in the slot with a side portion projecting laterally therefrom, said side portion being flattened relative to the opposite side portion of the loop, and one end of said spring being rigidly connected to said pin at one end of said slot.

9. A spring pin contactor comprising a pin having an externally threaded hollow stem and a portion provided with a longitudinal slot extending through it, and a looped spring wire having a straight portion projecting longitudinally into the hollow stem, said stem being large enough to receive only said straight portion of the wire, and the side portions of said loop projecting laterally from the opposite sides of the slot with the free end of the loop normally spaced from the opposite side portion thereof.

SAMUEL F. LYBARGER. ALFRED E. PELZ. 

